Seagate 1TB external hard drive not detected

I have a Seagate 1TB External Hard drive not being detected after i switched the laptop off while downlading a software file on the hard drive, that i couldn't stop & after the laptop came back up it couldn't detect the HD. Tha power comes on on the HD & the disk spins as it has an adapter & the USB connected to the laptop. Sometimes the light stayed on & lately it only flickers. Tried it on another PC doesn't get detected. Plz some help would b great. Thanks.

I have had about 15 Externals in my time, every problem i had was the same one, the circuitboard came away from the hard drive, all i did was unscrewed the whol thing pushed it all back together tightly

You cant run chkdsk if it not detected, First check it on Disk management , whether it detect or not.? If not some times it related USB cable issue, sometimes issue with connection jack of the Cable, or Sometimes it issue happens less power . Try to use 2 usb ports to get power by from Y cable.

Skim through Troubleshoot: Windows Won't Recognize Your USB Hard Drive
> Check Disk Management as someone else suggested above to see if the disk is recognized (there's an example in the Guide i posted)
> If the Drive is appearing in lower pane of Disk Management but not the drive letter in upper pane of Disk Mgt or in My Computer etc. the filesystem might be corrupt. You can try a data recovery tool like TestDisk